The present invention relates to a series of new pyridazine derivatives having a halo-substituted phenyl group at the 6-position and either a carbamoyloxy group (or the corresponding group in which one or both of the oxygen atoms has been replaced by a sulphur atom) at the 3-position or a substituted or unsubstituted hydrocarbyloxycarbonyl group at the 2-position and an oxo group at the 3-position. The invention also provides a fungicidal composition comprising these compounds and useful as an agricultural fungicide and a method of treating seeds, growing plants and land to protect plants from fungal attack by applying one or more of the compounds of the invention thereto.
Although very many different types of compound are known for use as fungicides, and, in particular, for use as agricultural fungicides, there is a continuous demand for new agricultural fungicides. This demand is partly due to the continuous development of resistant strains of fungus, which require new chemicals to combat them, and partly due to the inability of some known fungicides to met all of the requirements imposed upon them.
For example, our UK Patent Specification No. 1,533,010 (U.S. Pat. No. 4,052,395) discloses a series of 6-(substituted phenyl)-pyridazone derivatives which have excellent fungicidal activity. However, although the fungicidal activity of the compounds claimed in our earlier Patent is excellent, they have the disadvantage that they are not readily biodegradable and this can, in some cases, give rise to problems if biologically active residues are left on the land or in cultivated produce.
Accordingly, notwithstanding the excellent fungicidal activity of the earlier compounds, there is a demand for compounds useful as agricultural fungicides which, whilst retaining much of the activity of the earlier compounds, have the advantage of being more readily biodegradable.